1 # include_next.m4 serial 7
2 dnl Copyright (C) 2006-2008 Free Software Foundation, Inc.
3 dnl This file is free software; the Free Software Foundation
4 dnl gives unlimited permission to copy and/or distribute it,
5 dnl with or without modifications, as long as this notice is preserved.
7 dnl From Paul Eggert and Derek Price.
9 AC_DEFUN([gl_INCLUDE_NEXT],
11 AC_LANG_PREPROC_REQUIRE()
12 AC_CACHE_CHECK([whether the preprocessor supports include_next],
13 [gl_cv_have_include_next],
14 [rm -rf conftestd1 conftestd2
15 mkdir conftestd1 conftestd2
16 cat <<EOF > conftestd1/conftest.h
17 #define DEFINED_IN_CONFTESTD1
18 #include_next <conftest.h>
19 #ifdef DEFINED_IN_CONFTESTD2
22 #error "include_next doesn't work"
25 cat <<EOF > conftestd2/conftest.h
26 #ifndef DEFINED_IN_CONFTESTD1
27 #error "include_next test doesn't work"
29 #define DEFINED_IN_CONFTESTD2
31 save_CPPFLAGS="$CPPFLAGS"
32 CPPFLAGS="$CPPFLAGS -Iconftestd1 -Iconftestd2"
33 AC_COMPILE_IFELSE([#include <conftest.h>],
34 [gl_cv_have_include_next=yes],
35 [gl_cv_have_include_next=no])
36 CPPFLAGS="$save_CPPFLAGS"
37 rm -rf conftestd1 conftestd2
39 if test $gl_cv_have_include_next = yes; then
40 INCLUDE_NEXT=include_next
44 AC_SUBST([INCLUDE_NEXT])
47 # gl_CHECK_NEXT_HEADERS(HEADER1 HEADER2 ...)
48 # ------------------------------------------
49 # For each arg foo.h, if #include_next works, define NEXT_FOO_H to be
50 # '<foo.h>'; otherwise define it to be
51 # '"///usr/include/foo.h"', or whatever other absolute file name is suitable.
52 # That way, a header file with the following line:
53 # #@INCLUDE_NEXT@ @NEXT_FOO_H@
54 # behaves (after sed substitution) as if it contained
55 # #include_next <foo.h>
56 # even if the compiler does not support include_next.
57 # The three "///" are to pacify Sun C 5.8, which otherwise would say
58 # "warning: #include of /usr/include/... may be non-portable".
59 # Use `""', not `<>', so that the /// cannot be confused with a C99 comment.
60 # Note: This macro assumes that the header file is not empty after
61 # preprocessing, i.e. it does not only define preprocessor macros but also
62 # provides some type/enum definitions or function/variable declarations.
63 AC_DEFUN([gl_CHECK_NEXT_HEADERS],
65 AC_REQUIRE([gl_INCLUDE_NEXT])
66 AC_CHECK_HEADERS_ONCE([$1])
68 m4_foreach_w([gl_HEADER_NAME], [$1],
69 [AS_VAR_PUSHDEF([gl_next_header],
70 [gl_cv_next_]m4_quote(m4_defn([gl_HEADER_NAME])))
71 if test $gl_cv_have_include_next = yes; then
72 AS_VAR_SET([gl_next_header], ['<'gl_HEADER_NAME'>'])
75 [absolute name of <]m4_quote(m4_defn([gl_HEADER_NAME]))[>],
76 m4_quote(m4_defn([gl_next_header])),
77 [AS_VAR_PUSHDEF([gl_header_exists],
78 [ac_cv_header_]m4_quote(m4_defn([gl_HEADER_NAME])))
79 if test AS_VAR_GET(gl_header_exists) = yes; then
82 [[#include <]]m4_dquote(m4_defn([gl_HEADER_NAME]))[[>]]
84 dnl eval is necessary to expand ac_cpp.
85 dnl Ultrix and Pyramid sh refuse to redirect output of eval,
87 AS_VAR_SET([gl_next_header],
88 ['"'`(eval "$ac_cpp conftest.$ac_ext") 2>&AS_MESSAGE_LOG_FD |
89 sed -n '\#/]m4_quote(m4_defn([gl_HEADER_NAME]))[#{
90 s#.*"\(.*/]m4_quote(m4_defn([gl_HEADER_NAME]))[\)".*#\1#
96 AS_VAR_SET([gl_next_header], ['<'gl_HEADER_NAME'>'])
98 AS_VAR_POPDEF([gl_header_exists])])
101 AS_TR_CPP([NEXT_]m4_quote(m4_defn([gl_HEADER_NAME]))),
102 [AS_VAR_GET([gl_next_header])])
103 AS_VAR_POPDEF([gl_next_header])])